Relative or Absolute URLS The SEO Secure Answer
Site maintenance may well be made easier by using relative URLS and indeed transferring the domain is easier than if you absolute URLS too. Whilst the absolute URL method may take more time in terms of updating links on each page the reasons for its usage are strong.
Google for one may well miss some relative links, but from an seo point of view and security absolute URLs win hands down. Absolute URLS are much more secure when implementing a CMS change and less succeptable to hijacking.
Stick with the complete address, giving an entire path to the file is the way to go when possible.